The mysterious markings were carved into hidden floorboards at Knole, in Kent, in the 17th century, shortly before the king was supposed to visit the home in the wake of the Gunpowder Plot.
Archaeologists who were investigating a room built to accommodate royalty as part of ongoing conservation work at the house. They believe the witch marks were intended to ward off evil spirits, protecting the monarch in an era of superstition and fear of assassination.
A National Trust spokeswoman said, “A few months before the marks were engraved the infamous Gunpowder Plot of 1605 had caused mass hysteria to sweep across the country. Accusations of demonic forces and witches at work were rife.”
Using dendrochronology, or tree ring dating, archaeologists from the Museum of London Archaeology (MOLA) have now dated the marks to early 1606 and the reign of King James I.
Experts believe that craftsmen working for the owner of Knole house, Thomas Sackville, carved the marks in anticipation of a visit from King James I with the intention of protecting him from evil spirits.
According to the Trust the carved intersecting lines and symbols, also known as apotropaic marks, were thought to form a demon trap warding off evil spirits and preventing demonic possessions.
James Wright, MOLA buildings archaeologist, said: “King James I had a keen interest in witchcraft and passed a witchcraft law, making it an offence punishable by death and even wrote a book on the topic entitled Daemonologie. Using archaeology to better understand the latent fears of the common man that were heightened by the Plot is extremely exciting and adds huge significance to our research about Knole and what was happening at that time.”
It is part of investigative work that will continue throughout the house until 2018. The showrooms at Knole are currently closed to the public for winter conservation work but a series of guided tours of the marks will be conducted on November 20th and 21st.